Thanks Sandy, I'll give it a try. Hopefully my unidrum roller goes relatively the same speed as the jobo's slow speed you mentioned. And I'll go track down some sodium metaborate as all I have is sodium hydroxide here. Thanks for the tip.

Boy, the times for films are alot shorter for both fp4 and trix comparing pmk to pyrocat (for N dev. I've found online for pmk that is). Nice plus.

[quote="chrisl"]Thanks Sandy, I'll give it a try. Hopefully my unidrum roller goes relatively the same speed as the jobo's slow speed you mentioned. And I'll go track down some sodium metaborate as all I have is sodium hydroxide here. Thanks for the tip.

Boy, the times for films are alot shorter for both fp4 and trix comparing pmk to pyrocat (for N dev. I've found online for pmk that is). Nice plus.

Hi Chris,

Sodium hydroxide is very alkaline. I think that you could add just a bit of it, say 1/4 of a teaspoonful per liter, in substituion of the sodium metaborate or sodium carbonate. Mind you I have never done this but it will definitely make the pre-soak water alkaline and I don't *think* that it will do anything to interfere with the PMK.

And yes, times for Pyrocat-HD are quite a bit shorter than PMK, plus the fact that with the 1:1:100 dilution you get the slight increase in effective film speed.

In this neck of the woods (Australia) isopropyl alcohol is not available at pharmacies. What is readily available is Methylated Spirit which is mostly ethyl alcohol plus some denaturants to make you not want to drink it (typically methyl alcohol, a ketone, and denatonium benzoate whatever that is.)

I think it's the same as Denatured Alcohol sold in other countries.

Would this be a reasonable substitute for isopropyl alcohol? A post that I read somewhere suggested cheap vodka as a substitute. Would it be impossible to get the phenidone to dissolve without any alcohol?

Sandy
Thank you for this excellent article and for your contribution to the photographic community. At one time you have recommended adding 0.5 g of EDTA to 100 ml of both solution A and B. This does not appear in the formula you have now posted. I use distilled water in both stock and working solutions. Would EDTA be necessary when tap water is used? Bulent Ozgoren Istanbul Turkey

Sandy
Thank you for this excellent article and for your contribution to the photographic community. At one time you have recommended adding 0.5 g of EDTA to 100 ml of both solution A and B. This does not appear in the formula you have now posted. I use distilled water in both stock and working solutions. Would EDTA be necessary when tap water is used? Bulent Ozgoren Istanbul Turkey

OK, about the EDTA. After I made the recommendation to add EDTA to Stock Solutions A and B I received some negative reports from people who actually did this. What they told me was that EDTA killed the working solution. This really puzzled me because in my own work the addition of EDTA worked just fine. But then I remembered that there are two kinds of EDTA, Tetrasodium which is alkaline, and Disodium, which is acidic. Turns out that if you add the Disodium version to Stock B the solution will turn acidic within a relatively short time and the solution will be worthless.

There is no need for EDTA at all if you use distilled water for both the stock and working solutions, *and the pre-soak*. If you use tap water the addition of a small amount of EDTA, Tetrasodium, still makes sense. However, I am not going to put it back in the formula out of fear of folks confusing the two kinds.

In this neck of the woods (Australia) isopropyl alcohol is not available at pharmacies. What is readily available is Methylated Spirit which is mostly ethyl alcohol plus some denaturants to make you not want to drink it (typically methyl alcohol, a ketone, and denatonium benzoate whatever that is.)

Would this be a reasonable substitute for isopropyl alcohol? A post that I read somewhere suggested cheap vodka as a substitute. Would it be impossible to get the phenidone to dissolve without any alcohol?

First, the phenidone will dissolve without alcohol but it takes a long time, as a previous message confirms.

Second, any spirit should work fine for dissolving phenidone, the purer the better. Until someone tells me better my view is that any of the alcohols, in whatever form, will do the trick. Vodka should work fine because it is very pure, as should methyl alcohol and denatured alcohol. I am less sure about some of the aromatic spirits, such as gin, tequila, etc. But if they don't work just take a couple of swigs and try again. (Well, don't do that with the methyl alcohol and denatured alcohol, but should work fine with gin, tequila and vodka.)